Terrestrial telescope with digital camera

Abstract

A terrestrial telescope with digital camera has an imaging optical system having a group of objective lenses and an imaging element disposed at a position at which an optical image is formed by the group of objective lenses. An observation optical system is provided for observing the optical image transmitted by the group of objective lenses. An optical element is inserted into the optical axis so as to be retractable from the optical axis during imaging. The optical element has a transmission surface having a single-eccentric toroidal configuration with different curvatures in vertical and horizontal planes of the optical element for correcting the position on the imaging element at which the optical image is formed so that the position on the imaging element at which the optical image is formed remains substantially unchanged regardless of whether the optical element is inserted into or retracted from the optical axis of the group of objective lenses.

1. A terrestrial telescope with a digital camera comprising:
 a group of objective lenses having an optical axis; 
 an image pickup device disposed along the optical axis of the group of objective lenses at a position at which an image is formed by the group of objective lenses; 
 a quick-return half-mirror inserted into the optical axis and at a rear side of the group of objective lenses so as to be retractable from the optical axis during imaging; and 
 an observation optical system for observing an optical image reflected by the quick-return half-mirror; 
 wherein the quick-return half-mirror has a transmission surface having a single-eccentric toroidal configuration with different curvatures in vertical and horizontal planes of the quick-return half-mirror for correcting the position on the image pickup device at which the image is formed so that the position on the image pickup device at which the image is formed remains substantially unchanged regardless of whether the quick-return half-mirror is inserted into or retracted from the optical axis of the group of objective lenses. 
 
   
   
     2. A terrestrial telescope with a digital camera according to  claim 1 ; wherein the single-eccentric toroidal configuration of the transmission surface of the quick-return half-mirror corrects image-formation positional deviations in the horizontal and vertical planes and astigmatism arising from the image-formation positional deviations in the horizontal and vertical planes. 
   
   
     3. A terrestrial telescope with a digital camera according to  claim 1 ; further comprising means for decentering the transmission surface of the quick-return half-mirror with respect to the optical axis to correct a shift in the optical axis in a direction intersecting the optical axis. 
   
   
     4. A terrestrial telescope with a digital camera comprising:
 an imaging optical system having an optical path and including a group of objective lenses and an imaging element disposed along the optical path at a position at which an image of a subject is formed by the group of objective lenses; 
 an optical element disposed on the optical path of the imaging optical system between the group of objective lenses and the imaging element so as to be retractable from the optical path of the imaging optical system, the optical element having a transmission surface having a single-eccentric toroidal configuration with different curvatures in vertical and horizontal planes of the optical element for correcting the position on the imaging element at which the image of the subject is toned so that the position on the imaging element at which the image of the subject is formed remains substantially unchanged regardless of whether the optical element is disposed on or retracted from the optical path of the imaging optical system; and 
 an observation optical system for observing an optical image of the subject via the optical element disposed on the optical path of the imaging optical system. 
 
   
   
     5. A terrestrial telescope with a digital camera according to  claim 4 ; wherein the single-eccentric toroidal configuration of the transmission surface of the optical element corrects image-formation positional deviations in the horizontal and vertical planes and astigmatism arising from the image-formation positional deviations in the horizontal and vertical planes. 
   
   
     6. A terrestrial telescope with a digital camera according to  claim 5 ; wherein the optical element comprises a quick-return half mirror. 
   
   
     7. A terrestrial telescope with a digital camera according to  claim 4 ; further comprising means for decentering the transmission surface of the optical element with respect to the optical path to correct a shift in the optical path in a direction intersecting the optical path. 
   
   
     8. A terrestrial telescope with a digital camera according to  claim 7 ; wherein the optical element comprises a quick-return half-mirror. 
   
   
     9. A terrestrial telescope with a digital camera according to  claim 4 ; wherein the optical element comprises a quick-return half-mirror.